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School me on driveline vibrations!

Wookie316

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Ok, I need some help. I have a vibration that I can feel in the stick and I need to nail it down to what the issue is. If anyone has specs, or advice to what I should be doing, all help is greatly appreciated. Here is the build to give you an idea of where I am at.
71 Charger:
RMS front end (rack and pinion)
Tremec 5 speed
Mcleod clutch (see link). Originally purchased this kit for the 4 speed that was in the car. Kept the plate and changed the disk to one supplied by Tremec with the tranny when I decided to go 5 speed.
http://www.brewersperformance.com/proddetail.asp?prod=MCDP1023
Hydraulic clutch release bearing
Mcleod #464100 Flywheel
8 3/4" with 3:91 Eaton sure grip and strange axles
Super stock springs in the rear with Side A Links
Custom fab driveshaft (7290 joint), Has been balanced and rechecked once already.
4 wheel Wilwood disk brakes
weld in frame connectors
400 BB that is bored and stroked to 512

At some speeds (no load situation), there appears to be no vibration. 2000RPM in 5th in my car is about 67 MPH, it appears to have no vibration at that speed. If I jump up to 2100 and higher (as well as under load), I have a vibration I can feel in the stick (does not feel like a tire vibration).
Any ideas on what the issue may be?
Has anyone got a spec on the pinion angle? I know when the shop set it, the rear of my car sat much higher. Since it has settled over the winter, it may need to be changed. Looking for a spec range as well as where to measure? On the driveshaft?

This is frustrating because everything is new underneath, looking for some help and some direction. Any advice greatly appreciated. Thx.

0940_zpsd651e413.jpg
 
How heavy is it? My Keisler/Tremec runs similar rpms at 67 mph. 354 Dana. It has a stick rattle at higher rpms that settles down in 5th when loafing. Does it in all gears under load at higher rpm's. There is a fix from Keisler (if that is what it is) but not available for early TKO's.
 
Uuuhhh.....I don't know. Vibrations are a curse.

I just wanted to say that I think your Charger is bad-***, this is the first time I've seen it. I'm sure there's a thread elsewhere that gives up all the dirt: engine, trans, susp., and wheel/tire combo. I'll look for it now.
 
The driveshaft could be out of balance. Have same problem with my 68 Charger at 90 and above with 2 different sets of tires. And narrowed it down to the driveshaft just cant find anyone to high speed balance it around me
 
you need to drive it and make notes
is the vibration speed specific rpm specific gear specific torque specific ?
 
Your clutch itself shouldn't be an issue, but it really depends on how your engine was balanced! Was it balanced with the flywheel, and the shop "trimmed" the rotating assy with it on? was the flywhhel installed out-of-time with the crank for final assembly? Was the flywheel and pressure plate ever balanced? Is the engine internally or externally balanced? Some mixes and match parts from different engine/trans combo's
don't work because of balance issues. If it is in the rotating assembly, you will get the vibration at certain RPM's with the car in neutral not moving. If the vibration is only present when the car is moving, it's between the input shaft of the trans and the pinion gear in the diff. Good luck! let us know what you find!
 
It seems to be over 2000 RPM regardless of gear I'm in. Today when I buzzed her under load just holding the stick the vibration feels quite intense. When I back down to 2000 RPM it is quite smooth

As far as I know the flywheel was balanced to the rotating assembly but I'd have to confirm that. No howl from the rear end suggesting to me that its good.

Does anyone have a pinion angle spec so I can eliminate the easy stuff and start working down my check list? Thx.
 
if it is RPM related it is motor clutch or input to transmission or a misalignment did you check if the dowels where in the block before you bolted the bell housing on

Bruce
 
The shop that did the work assures me all of that is correct. Aside from pulling it all apart myself to check run out and dowels etc, I have to go on their word.
Want to try cheap and simple first and eliminate that before I get deep in it. Would rather check the cheap easy stuff first rather than dive into deep issues to only later find out it was a quick and easy fix.

Is there a spec on the pinion angle? Where is it measured?
Thx.
 
Typically, in mopars, pinion angle is -5 to -7, BUT, that's usually directed towards a drag style car with big, sticky meats.
Typical street cars run around -2 to -3, but considering this is a mopar AND a manual trans (which transmits more shock than an auto), PLUS, considering your suspension mods, -5 to -7 MIGHT apply.
Where are you set now?

pinion angle is your driveline angle, meaning. its the working angle of your rear and driveshaft together.
 
Yeah, about 3 degrees of pinion angle is good. What's important is they are equal but opposite front to rear. A way to visualize this is to imagine the output shaft CL and the pinion CL looking directly at each other as if there was a continuous shaft then change the elevation. That result would produce an angle equal on both sides.

A good way to check this is to get a fairly accurate level and starting at one end, rotate the trans yoke until the U joint cap is facing down and get a level reading off the machined surface. Then rotate the drive shaft 90 deg and get a reading off that U joint cap. The difference should be about 3 deg. Do the same with the rear yoke.

On my 66 Charger I had to shim the tranny mount a ton and add 1 deg caster wedge under the rear spring perch to get the angles correct. I'm not dead equal but pretty close. I still have a vibration but thinking it's tranny related at this point.
 
Start off 1st checking things to definitely narrow down where the problem is first and then move into more detail of that area.

You seem to be saying you have a RPM related issue at 2000 rpm in any gear, so now you need to narrow down is it the trans or motor.
If you have a shaft issue it's not going to happen every time you're near 2000 rpm in any gear, so we can eliminate that.
Could, but not likely be angles.
Most likely its at the trans or motor if at 2000 rpm in any gear you got a vibe.

So now you need to find out, motor or the front half of the trans or the rear half of the trans.
.
.
 
Have the car over at a buddies place for some other work. He has a lift, so hopefully we can get it in the air next week and check the pinion angles. When I drove out to his shop today, it almost seemed worse but that's probably in my head? Also was experimenting and am finding that lower RPM's also seem to have a vibrations at certain speeds. Is it a harmonic thing?
 
Does it vibrate in neutral with the car standing still? What happens if you push in the clutch?
 
No vibration when not in motion. With clutch engaged or released it makes no difference that I can feel.
 
Maybe take out the driveshaft,(may need to plug the tailshaft) and put it in several gears. May tell you if it's the trans. If no vibration, that leaves the driveline as the culprit.
 
Be sure you measure pinion angle on a "drive on" style rack with the suspension compressed. While you are under there, check for any kind of header, exhaust, mount or trans component that is making contact with the body of the car. It could be tailpipes hitting the rear bumper, the top of the tremec hitting the floor, the air cleaner contacting the wiper motor etc. Polyurethane is also pretty bad about transfering vibration not otherwise felt with rubber mounts.We chase vibrations here at the shop all the time and more often than not it is some type of contact issue.
 
Thx for the advice. Hoping to check a few things out next week. My week is crammed already this week!
 
Another thing that is very important is having the drive line angle only in one plane. Example: If you look down from the top of the car there should be no side to side deviation. The output shaft and pinion should be perfectly lined up. You only want the angle as you are looking from the side of the car. Since you have a tranny conversion make sure you don't somehow have a compound angle built in.

How is the slip yoke? You should not have excessive radial play.
 
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